This invention generally relates to an air filter in an air induction system in the engine of an automobile. More specifically to a hydrocarbon adsorbing material in the air filter.
Due to laws requiring the reduction of the levels of hydrocarbons that vehicles may emit into the atmosphere, it is necessary for automotive designers to include systems in vehicles to measure and control emissions. Hydrocarbons are released in a vehicle""s exhaust, as well as from the engine, even when the engine is not operating. Hydrocarbons remaining from engine reactions can leak out of the engine through the engine""s air intake.
The first step in reducing hydrocarbon emissions is to measure the level of hydrocarbons present in the engine system. Many methods have been utilized to measure the level of hydrocarbons in the exhaust. For example the hydrocarbon level in vehicle exhaust gas is measured by placing a hydrocarbon adsorbing material in the exhaust stream of the vehicle. The hydrocarbon adsorbing material is connected to a sensor. The sensor is connected to an on-board diagnostic system that monitors the exhaust emissions and notifies the operator when the hydrocarbon level exceeds a certain level. However, this method does not reduce the hydrocarbon emissions by any significant amount.
Apart from measuring the level of hydrocarbons in the exhaust, it is thus beneficial to reduce the level of hydrocarbons. One method of doing so is to absorb hydrocarbons from the exhaust flow via a filter-like device. A problem arises, however, wherein the adsorbing element eventually becomes saturated with hydrocarbons and is no longer able to function effectively. It would be beneficial to have a hydrocarbon-trapping device that would not have this limitation. Such an element could also be used to condition the air intake flow to increase engine capacity as well as for implementing a hydrocarbon-measuring feature.
Typically, the hydrocarbon-trapping device is formed of monolith carbon that is disposed in the air induction system of motor vehicles. One of the problems with such positioning of the hydrocarbon-trapping device in the air induction system is the risk of breakage due to vibrations, or due to throttle engine backfire. In addition to the loss of function of the hydrocarbon-trapping device, large pieces of carbon monolith may move towards the engine, thereby resulting in a premature failure of the engine of a motor vehicle. A separate hydrocarbon adsorber placed in the air induction system also results in more manufacturing steps, thereby driving up the cost of a motor vehicle.
Therefore, it is highly desirable to have a hydrocarbon-trapping device that substantially prevents carbon pieces from traveling to the engine and is not a separate component in the air induction system. Additionally, it is also desirable to have a hydrocarbon-trapping device that enhances the hydrocarbon adsorbing.
In one aspect of the present invention, an air induction system installed in a motor vehicle is provided. The air induction system comprises an air cleaner, a clean air duct, a mass air flow sensor.
In yet another aspect of the present invention, the air filter is provided with an integrated screen that is coated with a hydrocarbon adsorbing material. The screen is attached to the housing of the air cleaner.
In yet another aspect of the present invention, a method of adsorbing hydrocarbons using a hydrocarbon screen in the air cleaner is provided.
Further features and advantages of the invention will become apparent from the following discussion and the accompanying drawings in which: